6.0.0

I'm extremely stupid and didn't commit as I go. To anyone reading this
I'm extremely sorry. A lot of these changes are very broad and I plan on
releasing Babel 6.0.0 today live on stage at Ember Camp London so I'm
afraid I couldn't wait. If you're ever in London I'll buy you a beer
(or assorted beverage!) to make up for it, also I'll kiss your feet and
give you a back massage, maybe.

packages/babel-plugin-transform-es2015-parameters/src/index.js

@@ -1,7 +1,23 @@
+import type { NodePath } from "babel-traverse";
+import { visitors } from "babel-traverse";
+
+import * as destructuring from "./destructuring";
+import * as def from "./default";
+import * as rest from "./rest";
+
 export default function () {
   return {
-    visitor: {
-      // your visitor methods go here
-    }
+    visitor: visitors.merge([{
+      ArrowFunctionExpression(path) {
+        // default/rest visitors require access to `arguments`
+        let params: Array<NodePath> = path.get("params");
+        for (let param of params) {
+          if (param.isRestElement() || param.isAssignmentPattern()) {
+            path.arrowFunctionToShadowed();
+            break;
+          }
+        }
+      }
+    }, destructuring.visitor, rest.visitor, def.visitor])
   };
 }